Sound reproducer



Jan. 24, 1928. F. D. LEWIS SOUND REPRODUCER 2 Sheets-Sheet l an ue-ntoo Jan. 24, 1928.

F. D. LEWIS SOUND REPRODUCER Sheets-Sheet 2 Patented Jan! 24, 1928,

UNITED STATES PATENT OFFICE.

FRANK D. LEWIS, OF WEST ORANGE, NEJV JERSEY, ASSIGNOR TO PATHE PHONOGRAPH AND RADIO CORPORATION, OF BROOKLYN, NEW YORK, A CORPORATION OF NEW YORK.

SOUND REPBODUCER.

Application fi ed August 30, 1923, Serial No. 660,166 Renewed March 8, 1927.

My invention relates to the art of sound reproducers and more particularly to a con struction of loud speaker tor reproducing with an extremely fine degree of purity the electrical. vibrations received in radio broadcasting.

One of the objects of my invention 1s to provide a loud speaker reproducer for operation upon a fair strength of signal, without the requirement of a supplemental field, which is extremely iaithtui in reproduction of voice articulation and musical vibrations in the reception and reproduction of radio news, music, lectures and concerts Another object of my invention is to provide a loud speaker reproducer for operation with radio receiving apparatus with means for conveniently adjusting the relationship of the moving parts of the reproducer during a period of actual operation from the exterior of the casing whereby an adjustment is obtained in conjunction with any particular radio receiving apparatus which will afford reproduction without distortion and maximum enjoyment of the reproduced sounds.

A further object of my invention to provide a compact arrangement of mechanical parts including an electromagnet and pivoted armature for transforming electrical vibrations resulting in the reception of radio signals into sound vibration by reciprocal movement of a link member connected at one end with the armature and atthe opposite end with the apex of a conical diaphragm of the Actuelle reproducer type.

Another object of the invention is to provide a removable receiver cup arranged in a frame supporting the conical diaphragm with a removable link connecting the apex of the conical diaphragm with a pivoted armature within the cup, the pivoted armature being positioned adjacent an electromagnet operating structure and adjusted through a vernier movementcontrolled from the exterior of the cup for selecting the relative position of the conical diaphragm with reference to its peripheral supporting frame and the distance between the electromagnet poles and the operating armature.

A further object of the invention the on or a receiver cup for driving an ype of repro-ducer, which cup con 1 an oper ting olectroruagnet reinforced by a strong permanent magnet with an armature adjacent the magnet poles and pivoted at one side on a substantially frictionless double bearing, each bearing adjustable from the exterior of the casing and guided at its opposite sides by means of a U-shaped slotted resilient strip arranged to cooperate with the grooved head of a vcrnier screw, the screw passing through the receiver cup and controlled by a knob having means for locking the screw in any selected position against rotation arising out of continued vibratory movement of said armature.v

My invention will be more fully understood by reference to the accompanying drawings in which:

Figure 1 is a side elevation of an assembled loud speaker employing my construction of receiver cup and an Actuelle conical diaphragm carried in a peripheral frame which supports the receiver cup in a spider concentric with the central axis of the cone; Fig. 2 is a-rear view of my receiver cup assembled with the conical diaphragm showing the adjusting means on the exterior of the cup for selecting the position of armature bearings and fixing the relationship between the conical diaphragm and peripheral frame and the distance between the armature and magnet poles for securing the most pleasing tone quality of the radio broadcast; Fig. 3 is an enlarged vertical cross sectional View taken on line 33 of Fig; 2; Fig. 4 is a vertical sectional view of the interior arrangement of the receiver cup taken online 4& of Fig. 3; and Fig. 5 is a. horizontal cross sectional view taken on line 5-5 of Fig. l.

My invention employs an amplifying diaphragm oit' conical shape which is caused to vibrate piston like fashion within a pcripheral supporting frame for the reproduction of the received radio broadcast at relatively large amplitude distributing the re ceived broadcasting over a. large area. I do not employ an additional field coil in this rcproducer such as has heretofore been re quired in many forms of reproducers with the inherent demand for an additional storage battery or the additional drain of the source of storage battery supply used for lighting the electron tube filament circuits in the as sociated radio receiving circuits With the advent of the dry cell type f electron tube ,I am enabled to accuratel ,radio receiver to'secure reproduction at tonal quality without distortion and st 8 integral with the peripheral frame i. terminating 1n ring member 9.

it has been impossible to use previous types 1" extra iield winding loud speakers unless a storage battery were provided, and those types of loud speakers heretofore available and operating without extra lield coils have not satisfactorily reproduced the incoming energy with suliicient amplitude to render them desirable in lieu of a set'ol": head telephone receivers. Head telephone receivers are undesirable forms of reproducers in that they itz'iconvenieiit to wear and become tiresome to the listener, coi'isiderebly reducing the enjoyment. The h ad telephone receivers are further objectionable in that a number of head sets must usually be provided with an inherent diminution in s. nal strength as the number of head sets in in creasec.

vBearing in mind the disadvantages exist-- ent in prior types of renroducers I have improved the construction of the loud speaker described in in; 7 reading application with Eugene A. ie-7.3211111, Serial Number 569,692 filed J'u e 192:2 whereby adjust each loud i any oar-tics 1r good la [e speaker for operation upu the pe 'ipheral frame 1 by removable annular "rim l enabling a free piston like movement of the diaphragm Within :a limited dn si-on. A spider for supporting the receiver cup 5 is provided, formed of arms 6, 7 and. and The receiver cup 5 is secured and set in ring member 9 by means of set screws 10. I

The receiver cup 5 is tubular in form having a portion o'li' relatively smell diameter fitting into ring member 9 and a portion ll of relatively larger diameter which forms a housing for the eleetri :al and J-nechanicel operating mechanism of the loud speaker. r

circular cover 112 having :1 n annular skirt 144:

mas net windings 16 and 17" contained thereon between flanges 16 and 17. The pole pieces 16 and 17 aresecured in position by permanenthorseshoe 18 and 19 through which screws 20 and 1 are passed M ll.

from the front of the cover 12, andsecured' p9 through a threadeby nuts on lllG other side of the permanent magnet The electromagnetic windings 16" and 17! are connected in series and the ends brought out to terminals 22 and. 24; which are well insulated from the receiver cup by insulating washers and'bnshings. Binding" posts 22 and 2d are positioned on the outside or the receiver cup providing a convenient (TOIQHC means between the output circuit of the radio receiving apparatus and the electronic etic 'wimlin. x

I mount a bearing); block 25 winin the cover 12 adjacent the 'electromagnets. 'A double bearr ng provided formed by slender screws 26 and 27 passing; through hearing block 25, said sc ews beingv provided with slender grooved heads 26 and 27 accessible ;.rom the ;e1.'ior of the css in such mam outer the bearin block. The screws 26 and 2? terminate in linel ground point ends '26" end 27 which provide beari QS for armature member 28 The armature. member centered on the bearing points 26 a1. 1 vand resili itly pressed thereagai-nst by means of u-djt ble screw and coil spring 30. The weight of the armature is rec Wed'to a minimum, thereby substant eliminating mechzuiiical inertia by reducing: its dimension at 31. The end of the armature opposite the pivotal mounting lies directly adjacent the electromagnet pole pieces 16 and 17. A 5,; shaped resilient strip 32 is secured by means of screw to the end of the armature opposite the magnet The strip 32 extends substantially beyond the electromagfnets l6 and 17 and provided with a cen tral slot throughout a portion of each side of the U. An QTi'tQHdG/(l Vernier screw 35 bushing 36 in 7 l2 and is provided the interior end. with e. grooved portion 87 and heed 38. The U shaped strip 32 is urrangird so that its slotted sides PLU' 'l'ZC G on citliicr si oi the portion 3'? anderc confined within limits of vertical mov-emcn b the shoulder 39 and head 38. V

The rotative movement of screw 35 is controlled with n predetermined limits by an arrangement 0t parts which cooperate to maintain the screw member 3:3 in any particular position. Cu sl' aped annular rings 40 and ell are provided concentrically tiered around screw member coil spring 4L2 is disposed between the cup i s 40 and all serving to constantly ofl'er h lotion grip between the inner surface of the hand leuoh 43 and the surface of the cover 12. A flat priuectin arm 44 secured adjacent the lower surrace of the nand knobv 43 by means of an'integral. annular ring. The hand knob 1-3 is properly located on the screw 35 andthen set screwj45 tightener to lock the hand knob 43 in a selected position. A stop pin 46 is providedwhich Ill) cooperates with The rotation of hand knob L3 not only selects the distance between the armature 28 and the pole pieces 16 and 17 but also serves to finely adjust the position of connecting link 48 which connects at its extremity with the apex 4-9 of the conical diaphragm 3. The electromagnetic mechanism within the casing 11 is protected by means of felt partition 50 across the circular extension 5.

In operation oi the loud speaker it will be apparent that connection with the last stage of audio frequency amplification may be made through terminals 22 and 2st. The loud speaker is adjusted for reproduction at maximum tone quality first bylongitudinally sliding the circular extension 5 backward or forward within ring member 9 until the desirable tension secured on conical diaphragm 3 which tree to move within narrow limits by reason of the annular rim portion 4. lVhen this desired position is obtained the electromagnetic mechanism is locked in this position by means 01 set screw 10. The armature 28 is located in parallelism with the pole pieces 16 and 17 by adjusting the position of the bearing screws 26 and 27 by turning heads 26 and 27*. The armature tension is then adjusted by means of screw 29 and the link 48 attached and the complete electromagnetic mechanism inserted in the casing 11.. The link 48 is then connected with the apex of the conical diaphragm at 49. The hand knob i3 may now be adjusted to tinely regulate the distance between the armature 28 and the pole pieces 16 and 1'7". It will be noted that all adjustments may be made from the exterior of the casing during actual operation of the loud speaker.

While I have described my invention in certain limited embodiments, it is to be understood that modifications may be made without departing from the spirit of the invention and that I intend no limitations upon the invention other than are imposed by the scope of. the appended claims.

WVhat 11 claim and desire to secure by Letters Patent ot the United States is as follows:

I 1. A loud speaker for reproducing electrical vibrations comprising in combination a support, a circular frame carried by saidv support, a conical diaphragm peripherally mounted on said frame, a plurality of radial arms secured to said frame and terminating in a central ring, a receiver cup having a portion mounted in and slidable axially through said ring, electromagnetic operating mechanism carried by said cup. a. link extending through said cup portion and said may be l111- ring and connected at one end with said electromagnetic operating mechanism and at the other end with the apex of said conical diaphragm whereby vibrations imparted by said electromagnetic mechanism cause said conical diaphragm to translate said vibrations into sound waves, and means for ad justing the position of said electromagnetic mechanism with respect to said diaphragm.

2. A loud. speaker for reproducing elec trical vibrations comprising in combination a support, a circular frame carried by said support, a conical diaphragm, an annular ring on said diaphragm secured in said frame, a plurality of integral radial arms extending inwardly from said frame and terminating in a central carrying member, an electromagnetic operating mechanism having a portion mounted in and slidable axially through said central carrying member, and a link positioned in the line of the axis of said carrying member and connected. at one end with said electromagnetic operating mechanism and at the opposite end with he apex of said conical diaphragm whereby said electromagnetic operating mechanism may be fixed in position in said :entral carrying member to impart that degree of vibration to said diaphragm which aflorcs reproduction of maximum tone quality.

3. A loud speaker for reproducing electrical vibrations comprising in combination an electromagnetic mechanism having an electromagnet, an armature, a pivoted bearing for one end of said armature, yieldable means constantly pressing said armature against said bearing, a resilient U shaped slotted strip secured. to the opposite end of said. armature, and a vernier adjusting screw having means cooperating with. said slotted U shaped slotted strip for selecting the position of said armature with respect to said electromagnet.

4. A loud speaker for reproducing electrical vibrations comprising in combinationv an electromagnetic mechanism having an electromagnet, an armature, a pivoted bearing for one end of said armature, yieldable means constantly pressing said armature against said. bearing, a'resilient U shaped slotted strip member secured to the opposite end. of said armature, and vernier adjusting screw having a groove adjacent one end, said groove having a length approximately equal to the distance across the sides of said U shaped member, said slotted U shaped member cooperating with said groov'e where by the position of said armature relative to said electromagnet may be adjusted by rotating said. screw.

A loud speaker for reproducing electrical vibrations comprising in combination an electromagnetic mechanism having an electromagnet, an armature, a U shaped strip till having one side longer than the other, with said longer side secured along the center line to sai d armature at one end thereof, a double bearing for said armature at the opposite end thereof, one of said bearings disposed on each side of the center line of said armsture, resilient means yieldably forcing said ari'nature constantly against said bearings, and iz-ieaas cooperating With said. shaped strip for selecting the position of said armature with respect to said electromagnet for reproduction of electrical vibrations at maximum tone quality.

6. A loud speal-ier for reproducing electrical. vibrations comprising in combination a support, a circular frame carried by said support, a conical diaphragm peripherally mounted on said frame, a plurality of radial arms secured to said frame and terminating in a central ring, a receiver cup having a eircular casing, a circular aiztension on casing of smaller diameter than said receiver cup, electromagnetic operating mechanism carried Within said cup, a link extending 7 through said circular extension and connecting said electromagnetic operating mecha- 'nism With the apex of said conical dia phragm, and means for selecting and fixing the longitudinal position said circular extension Within said central ring whereby to fix-the tension between said diaphragm and said armature causing the electrical vibrations from said electromagnetic mechanism to be reproduced at maximum tone quality by said diaphragm.

7. A loud speaker for reproducing electrical vibrationscomprising in combination a support, a circular frame carried by said support, a conical diaphragm peripherally mounted on said frame, a plurality of radial arms secured to said frame and terminating in a central ring, a receiver cup having a cirphragm, means in mg said circular cular casing, a circular extension on said casmg oft smaller diameter than said receiver cup, electromagnetic operating mechanism carried Within. said receiver cup, a linl: e,

tending through said circular extension and connecting said electromagnetic operating mechanism with the apex of said conical diasaid central ring for lockextension in a selected longitudinal position for lining the tension betweez'i said armature and said diaphragm,

and means operative from the exterior of said recei'. er cup for minutely fixing the tension between said diaphragnn and said armature causing electrical vibrations from said electromagnetic mechanism to be reproduced. said diaphragm;

8. A loud speaker for reproducing electrical vibrations comprising in combination a support, a circular frame carried by said support, a'conical diaphragm peripherally mounted on said frame, means carried by said support for, centrally locating a receiver a mature, resilient means cup relative to said diaphragm, an electromagnetic mechanism including an electroniagnct and an armature contained Within said cup, a connecting link between said armature and the apex of said conical diaphragm, and springpressed rotatable means operative from toe exterior oi said casing for adjimting the position of said armature relative to s; vibrations from said electromagnetic mechanisn'i are reproduced, by said diaphragm at nnuqimum tone quality.

' 9. loud speaker for reproducing electrical vit ations comprising in combination a support, a circular f ame carried by said suppcrtqa conical d .phragm peripherally mounted on said frame, a receiver cup centrally carried by said frame and provided with a cover, an e. ctromagnetic mechanism carried by said cover and portion oi. said cup incluI' an electromagnet, an armature, a pair or pivotal bearings for one end of said constantly and :ldably urging said armature in the direction of said electromagnet, a U shaped resilient member secured to the opposite end of said armature,a link connecting said armature with the apex of said diaphragm, and means extending through said U shaped member and s 'd cover for adjusting the position of said armature With respect to said electromagnet, said pivotal bearings and said last mentioned able from the exterior of said cup for selecting that relationship of parts by Which electrical vibrations are reproduced by said dia phragm at maximum tone quality;

10. A loud speaker for reproducing electrical vibrations comprising in combination a support, a circular frame. carried by said support, conical diaphragm peripherally mounted on said frame, a receiver cup cen said bearing in the direction of said magnet, means exterior of said cup i01 21(.l]ll8tll'lg the tension of said spring means, a U shaped slotted resilient member secured to the opposite end of said armature. a screw mounted in said. cup having;' a groove'adjacent the inner end thereof cooperating with said slotted U shaped member, and spring pressed means whereby saidscrew ma be .ated from the exterior of said cup and rom :vely

held in a selected position for maintainingv said armature spaced with relation to said electromagnet for reproduction of electrical vibrations by said diaphragm at n'iaximum tone quality. 11. A loud speaker for reproducing electrical vibrations comprising in combination a support, a circular frame carried by said d elci'ztromagnet Wherebyxelectrical means all bein ad'ust support, a conical diaphragm peripherally mounted on said frame, a receiver cup centrally carried by said frame, an electromagnetic mechanism carried within said cup in cluding an eiectromagnet, an armature, a pivotal bearing for one end of said armature spring means pressing said armature against said bearing in the direction of said magnet means exterior of said cup for adjusting the tension of said spring means, a U shaped slotted resilient member secnred to the opposite end 01 said armature, a screw mounted in said cup having a groove adjacent the inner end thereof cooperating with said slotted U shaped member, a hand knob and spring pressed means surrounding said screw exterior of said cup and disposed be tween said hand knob and said cup whereby said screw may be rotated from the exterior of said cup and positively held in a selected position for maintaining; said armature spaced with relation to said electromagnet for reproduction of electrical vibrations by said diaphragm at maximum tone quality.

12. A loud speaker for reproducing electrical vibrations comprising in combination a support, a circular frame carried by said support, a conical diaphragm peripherally mounted on said frame, a receiver cup centraily carried by said frame, an electromagnetic mechanism carried within said cup in eluding; an electromagnet an armature, a pivotal bearing for one end of said armature a U shaped slotted strip secured to the opposite end of said armature, a screw threaded adjusting; member passing through said cup and slidably secured in said slotted U shaped strip said member havina a hand knob at its extremity exterior of said cup, flanges concentric with said member, a coil spring disposed between said flanges, and a stop for limiting the rotation of said member whereby said U shaped strip may be raised or low ered and positively set in a selected position for fixing the position of said armature with respect to said electromagnet to enable electrical vibrations to be reproduced by said diaphragm at maximum tone quality.

In testimony whereof I aflix my signature.

FRANK D. LEWIS. 

